[Test] java/awt/image/VolatileImage/GradientPaints.java times out on Linux

Details

Description

. The fix for JDK-8198613 removed the VM option -Dsun.java2d.opengl=True from all the test cases.
. This implies that the respective test case will now get executed on the default pipeline of the host machine.
. The test- GradientPaints.java has been observed to fail with timeout on xrender pipeline.
. Excerpts from the JTreport files are-